WIDIA GTD High-Performance Spiral-Point Tap for Multiple Material

These taps have a unified thread standard. UN coarse (UNC) taps have fewer threads per inch than UN fine (UNF) taps. Compared to UNF taps, UNC taps perform better in threading applications on brittle materials and are less likely to cross thread. Coarse threads can also withstand more physical abuse than fine threads. UNF taps have more threads per inch than UNC taps. Compared to UNC taps, UNF taps perform better in threading applications on thin-walled workpieces and hard materials. Fine threads provide more tensile strength and shear strength than coarse threads. The black-oxide finish on these taps retains lubricants to improve the taps' wear resistance and chip flow. Black-oxide taps should only be used on ferrous metals.